Radio apparatus



Apri 5, 2- J. E. GARDNER RADIO APPARATUS Filed Aug. 17,1926

INVENTOR Patented Apr. 5, 1932 UNITED STATES PATENT? OFFICE.

101m 11 GARDNER, or cmca'eo; ILLINOIS, ASSIGNOR To emesa'Y-enonow company;

or CHICAGO, ILLINOIS, A conronamon or ILLmoIs RADIO APPARATUS Application filed has 17, 1926. Serial 1%. 129,717..

My invention relates in general to radio ap aratus, and more particularly to such ra io apparatus as employ'in combination a talking machine.

One of the objects of my invention is to provide automatic tuning means, so that the radio receiving set will automatically function to tune in any station that may be broadcasting. y l Another object is to provide means for automatically tuning in any predeterminedsta tion. Another object is to provide means for enabling a talking machine and radio receiving combination to function, using the l usual commercial sources of electrical energy,

whether this energy be alternating or direct current. a v

Further objects are to provide an improved means for-automatically stopping the turn table of the phonograph when the end of the recordis reached, to provide improved means for energizing the radio receiving set when the record stops; to automatically tune in any station that happens to be broadcasting, and to tune in another station when the broad casting from the first selected station ceases, and to automatically disconnect the electric energy from the tubes employed in the ma-.

chine when there is no broadcast reception being had, or no record being played.

There are other'objectsof my invention, which, together with the foregoing, will be described in the detailed specification which is to follow, reference being had to the accompanying drawingforming a part hereof.

The type of talking machine which I employ in carrying out my invention,-and the apparatus employed therein has been described in my co-pending application, Serial Number 123,528, filed July 19th, 1926. Reference is had to this application for a more complete description of the apparatus.

Briefly, the apparatus consists of the usual talking -machine of the electric reproduce ing type, such as the machines going under the trade names, Electrola and Panta-' trope. a

In accordance with the apparatus and features described in the above cited co-pending application, relays are provided for controlling the automatic stopping of. the turn-table of the machine. The automatic re-setting of the radio switch over a radio switch back, as well as the automatic tube cut-off.

Referring now to the drawing, the talking machine itself comprises a tone arm. 5), magnetie pick-up (6), electric motor table (8) and the record (9). Electric energy is supplied to the machine from a source of current such as (74), and is transformed by the power equipment (10), to electric energy of the character necessary to bring about the proper operation of the equipment. The power equipment (10), comprises a ballast tube "(11), transformer (12) rectifiers (13 and 14), and a resistor (15) that functions in a manner similar to a potentiometer, to

provide means for obtaining the proper voltages necessary for operation of the device. Amplifying triodes (16 and 17) of the usual type'are also provided for amplifying the electric currents generated by the magnetic pick-up. The loud speaker (18) of the usual cone type is associated with the output circuit of the power amplifier (17 through the transformer (19), the secondary of which is variable, so as to control theamount of 1 energy supplied to the loud speaker. A milliammeter relay (20), is also associated with the output circuit of the amplifier (17) through a transformer (46). Relays (22 and 23) of the usual type employed in the automatic telephone art are adapted to be controlled by the operation of the milliammeterrelay (20).- The automatic stopping and I e-setting device, comprising the stoppingmagnet (29), and the resetting magnet (34), is essentially of thefsame character described in theabove mentioned co-pending application. The cont-acts (42 and.44) are also the typementioned in the co-pending application. The contacts (42) are adapted, to be operated when the tone arm (5) is moved into a position that corresponds to the beginning of a record, while the contacts (44) are operated when the tone arm reaches a position shortly before the end of the rec- 0rd.

The radio receiving set comprises an antenna (90), that is of the aperiodic type; that 7), turn' is, it is tuned so that it will pick up any frequenc of carrier wave that is being broadcaste a detector triode (54), an amplifier triode (57) are provided in the receiving set. The grid circuit of the detector triode is adapted to be tuned by the condenser (61).

The rotor of the condenser (61) is also adapt- P ed to be operated by a stepping magnet (62), through a pawl and ratchet (60). A cam switch (91') is provided so that the springs are closed at all times except in a predetermined normal position of the rotor plates of the condenser.

The output circuit of the amplifier (57) is adapted to be connected to the grid or input circuit of the amplifier triode (16). The output circuit of the amplifier (57) is also associated with the milliammeter relay (65). The relay (66) is a latching relay having a release coil (77). The armatures (7 5 and 76) of the relay (66) are adapted to be maintained in operated position even when the relay (66) is de-energized by the armature (87 of the relay (77 The relay (67) is a dashpot relay. The dashpot is operated so as to 've this relay a relatively long time constant in operating. The time constant may be ten minutesor longer beforethe armature (78) closes its associated circuit. The relay (68) may be of any usual and well known type. The relay (69) is ing a time constant that is considerably less than the time constant of the relay (67) ,say five minutes for example. The relay (7 O) is the usual type of telephone relay. .The relay (72 is a double coil relay, and is provided wit a tuned armature (86), the frequency of which may be adjusted. The relay (72) ma be of the usual type employed in socal ed harmonic converters in the automatic telephone art. The armature (86) is tuned so as to respond to a frequency of 60 cycles. The relay (71) is a high impedance relay, and is adapted to respond only to direct current.

The'key (48) is a three position key, the normal position of it being shown. The operative positions are shown by the dottedlines A d N A.

The push button switch (28) is employed for the initial eration of the device.

Having brie y described the apparatus shown in the drawing, I will now-explain its detailed operation. To assist in understanding the operation it will be assumed that the operator desires to play the phonograph without any auxiliary features. Under these conditions the key (48) remains in its normal another dashpot relay, havg I p I the tone arm '(5) into the starting position,

position as shown in the drawing. The operator will press the button (28). When the push button (28) is pressed there is a circuit completed, from one side sourceof current (74) through the springs of the switch (28) relay (66), to the other side of the source of alternating current. The relay (66) is an alternating current relay, although it will also respond to direct current. In this instance it will be assumed that alternating current is obtained from source (74). The relay (66) is energized to attract its armatures (75 and 76) which are latched in operated osition by the functioning of the armature (87) of the rela (77). Alternating current is now connecte to the primary of the transformer (12) in series with the ballast tube (11). The ballast tube (11) inerely acts as a reactance to limit the current flow in this circuit. Inasmuch as there is alternating current flowing in this circuit, the high impedance relay (71) is not operated at this time. The rectifiers (13 and 14) immediately start to operate to supply direct current to the ampli ying device (16 and 17). As soon as the rectifiers function, the lamp (45) is lighted, so as to indicate to the operator that energy is connected to the set, and he may release the push button (28), thereby opening the circuit of the relay (66). The relay (66) is de-energized though its armatures (75 and 7 6) are maintained in operated condition.

The operator will now place a record (9) upon the turn-table (8), and will move the tone arm so as to position the needle of the magnetic pick-up (6) upon the first roove of the record. By the movement of the contacts (42) are closed and there is a circuit completed that extends from one connection of the potentiometer through the springs (42), resetting magnet (34) to the mid-point of the potentiometer. The connections on the potentiometer determine the voltage in any given circuit. The midoint of the potentiometer is zero potential. n the present instance, it has been found that 48-50 volts brings about 'thebest operation of the relays employed. However, a greater or lower voltage maybe used, depending upon the design of the relays employed. The re-set magnet (34) is energized to move the brake (32) from engagement with the under side of the turn-table (8), against the tension ofthe spring (33). The brake (32) is latched in this position by the action of the extension (31) passing over the catch on the armature of the release magnet (29). This operation also brings about the opening of the springs (36), and the closure of the springs The closure of the springs (35) completes a circuit for motor (7). The motor (7) immediately init a es the rotation of the turn-table (8), carrying the record (9). As the record rotates,

; the sound indentations in the spiral groove thereof brings about the vibration of the needle of the magnetic pickup, and cause a variation in electrical energy in the circuit that extends to the grid of the amplifier triode (16). A resistor and condenser (91) is bridged across this circuit, so as to eliminate the usual mechanical noises obtained-by the engagement of the needle with the record. The current that is applied to the grid circuit of the amplifier (16) is governed by the sound indentations in the record (9) These voice, or sound currents, are amplified and applied to the grid of the power amplifier (17). The power amplifier (l7) amplifies these currents and supplies the energy to the loud speaker (18). The volume of' this energy is controlled by the variable secondary or the transformer (19). The loud speaker 18) functions in the usual manner to transform the variations in electrical energy into sound waves. The amplified sound currents are also applied to the armature (21) of the milliammeter relay; (20), through the small rectifier, or crystal detector (47). The detector (47) operates to v rectify the alternating current and apply it to the armature (21) of the'milliammeter relay (20). The'armature of the milliammeter relay (20) turns so as to move the contact making member (92) away from engagement with the contactmember (93). So long as there ever, the de-energization of this magnet is without particular function at the present time, as its armature is latched by the operation of the armature (30) of the release magnet (29).

Shortly before the end of the record, the springs (44) arebrought into engagement. The point at which these. springs engage is determined by the shortest record that is to be played. The springs are adjusted so as to 1 engage shortly before the termination of theshortestrecord. If the records are all provided with a spiral groove, it is not necessary that such adjustment be made, so long as the springs engage before the cessation of the inward rotation of the tone arm This has been explained more in detail in the above mentioned co-pe'nding application;

When the springs (44) are broughtinto engagement t ere is r a circuit completed from the connection on the potentiometer through the springs (44-), back contact and armature (2'5), slow-acting relay (23) to the mid-point of the potentiometer. The slow -acting relay (23) is energized to open a circuit of the motor (59) at armature (26).-

When sound indentations in the record are no longer encountered by the magnetic pickup, there are no sound currents present in the output circuit of the power amplifier (17),

'consequently the armature (21) of the milliammeter relay is de-energized, and the contact making member (92) is brought into engagement with the contact member (93). A circuit is thereupon completed that extends i(.'ro1)n the connection of the potentiometer 15 her (93), contact making member (92), relay (22), to the midpoint of potentiometer.

Relay (22) is energized to prepare a point in the circuit of relay (69), at armature (24) and to open the circuit of the slow-acting rela, (23) at armature (25).

val of time to complete a circuit that extends from the connection on the potentiometer (15) through the springs (44), armature -(27) and its back contact, release magnet (29) to the mid-point of the otentiometer. Release magnet (29) is energlzed over this circuit and operates to attract its armature (30), thereby releasing the latch (31) so that it restoresthe normal operation of the brake (32). The brake (32 engages the underside of the turn-table 8) bringingthe turntable to rest. Thecam extension (37) is The slow-acting re ay (23) is de-energized for a short interpoint in the circuit of the release magnet (29) i at armature (27) and to open a point in thethrough the springs (44) contact memoperated so as to open'the circuit of the motor (7) and to prepare acircuit for the rela (68). The rotation of the turn-table (8) ceases, and the record is brought to a stop.

In the event that another record is played,

the tone arm is moved as before, and the operation occurs as described. In the event that no further 0 eration is performed by the operator, the'e ectric energy is automatically disconnected from the device. This result is brought about by the operation of the armature (24) of the relay (22), wherepy a(ci;'cuit.is completed 'for the dashpot reay 6 gized 0 a considerable interval of time to complete a circuit at its armature (78) for the release coil (77).

The release coil (77) is energized to attract its armature (87) thereby permitting the armatures (75 and 76) of the relay (66). to restore to normal. By the later operation electric energy is disconnected from the machine.

' The above is the o eration of the device when the talking mac ine or phonograph is played. Y It will now be assumed that it is desired to operatethe radio receiving set immediately after the desired record is played. In order to do this, the key (48) is operated to position A. The operation in playing the record proceeds substantially in the same The dashpot relay (67) 'isenere manner as before described up to the energizationof the relay (22), the e-energization of the relay (23) and the energization of the release magnet (29). Now when the springs (36) are closed, a circuit is complete that extends from the connection on the potentiometer springs (36), springs (52), of the key (48), relay (68) to the mid-point of the potentiometer. The relay (68) is energized to complete a circuit for the dashpot relay (69) at armature (80) and for the filament circuits of the triodes (54 and 57) v at armatures (81 and 82), while at armature (83) an electrical potential is connected to the contact making member (94) of the milliammeter relay By this connection there is a circuit completed for the relay Relay (70) is energized, but its operation is without particular function at this time. The triodes (54 and 57) are energized to render them receptive when the condenser (61) is properly tuned, so that the input circuit of the detector (54) is resonant to a broadcast carrier frequency.

If the operator does not play a record, the slow operating relay (69) is energized to operate its armature (79), thereby completing a circuit that extends from the connection on. the potentiometer by way of back contact from armature (26), armature (79), motor (59) to the mid-point of the potentiometer. The motor (59) is immediately operated to bring about the,rotation of the rotor of the condenser (61) at a relatively slow speed. The movement of the rotor of the condenser changes the tuning of the input circuit of the detector (54). Whenever the input circuit of the detector becomes resonant to the frequency of a carrier wave, the detector operates in the usual manner to apply the sound potentials to the input circuit of the amplifier (57) where they are am plified and applied to the amplifier (16) and thence to the power amplifier (17). The loud speaker (18) thus functions to transform the received broadcast into sound waves. As soon as any station is tuned in in this manner, the armature (21) of the milliammeter relay (20) is operated so as to bring the contact-making member (92) out of engagement with the contact member (93). The relay (22) is immediately de-energized to complete a circuit for the slow-acting relay (23) at armature (25) and to open the circuit of the relay 69) at armature (24). The relay.

69) is so constructed that While it is slow to energize. its de-energization occurs relatively quickly. By the de-energization of relay (69) the circuit of the motor (59) is opened, and the rotation of the rotor of the condenser ceases. The energ zation of the slow-acting relay (23). also opens another point in'the circuit of the motor (59) at armature (26), and opens the circuit of the release magnet (29) at armature (27). The

cessation of the motor operation as described causes the cessation of the movement of the rotor of the condenser (61) and consequently the input circuit of the detector (54) remains resonant to the frequency of the station that has been tuned in. It will thus be seen that by the functioning of the device described, a broadcasting station may be automatically selected by the radio receiving set.

For proper tuning operations, the contacts (92 and 93) of the milliammeter (20) may be adjusted so that it requires a considerable amount of current flowing through the armature (21) to cause the contact to disengage. This will insure that the station tuned in, will have the desired volume. Of course this volume may also be adjusted by the operation of the transformer (19).

During the momentary pauses in the broadcast, the contacts (92 and 93) may be closed, and the slow-acting relay (23) will be deenergized to complete a circuit for the slow operating relay (69). The time constant of the relay (69) is so fixed that the armature (79) will not engage its contacts for a longer interval of time than that that occurs in the broadcast, consequently the energization of this relay is without particular function. In-

asmuch as the relays (22 and 23) are intermittently operated there may be some sparking at the contacts, which may cause noises in the radio receiving set. However, this sparking may be ent rely eliminated by the use of non-inductive resistance and condensers that are usually employed in the telephone art.

If still further precaution is desirable, relay equipment may be enclosed in an iron case, and this case grounded so that the radio set will be effectively shielded. \Vhenever the relay 22) is energized upon the contacts 92 and 93) closing, a circu t is completed for the slow to operate relay (67), but this relay has a longer time constant than the relay 69), consequently its operation will be without particular function during the broadcasting.

When the broadcasting station signs off, there will be no sound component present in the current in-the output circuit of the power amplifier (17 The armature (21) of the relay (20) will-be de-energized and the contacts (92 and 93) will be closed to complete a circuit for the relay (22). The relay (22) is energized for a short interval of time to complete a point in the circuit of the motor (59). By the operation of the armature (24) of the relay (22) a circuit is completed for the slow to operate relay 69). After a considerable period of time the slow to operate relay (69) causes its armature to engage its contacts thereby completing the circuit for the motor (59). The motor (59) functions in the same manner as before to tune in another broadcasting station, if it happens to be operating at this time. The tuning in of this station and the stopping of the motor occurs in substantially the same manner as before. Broadcasting stations will continue to be tuned in consecutively, so long as there are an stations broadcasting. I

f there are no stations broadcasting, the voice current relay (20) will not be opera tive, and the slow to operate rel'ay (67 will have suflicient time interval. to cause its armatures to engage their associated contacts, thereby completing the circuit for the relay (77) The relay (7 7) flmctions to disconnect the energy from the equipment in the manner before described. All the relays in the device are thereupon de-energized, and their associated circuitsare restored to normal.

In the event that it is desired to shut down the radio receiving set at any time, the key (48) is restored to its neutral position, whereupon the circuit of the relay (68) is open, so that the automatic tuning equipment, and

the radio receiving equipment is disconnected. The relay (67) then functions as before to bring about the disconnection of the electrical energy from the device. 7

- It sometimes occurs that while one is L80 listening to a broadcast reception the station requests that the listeners stand by for an interval of time. 'monotony of this wait, it is sometimes desirable that the phonograph be placed in operation. It may be that at this time a play is being broadcast, or something of that nature,

and itis not desired to miss any ofthe broadcast. In order to bring about proper functioning of the equipment in these conditions, the key (48) is brought to the position N A, and the phonograph is started in the same manner as beforedescribed. When the key is thrown into position N A the spring (51) is caused to engage its working contact, whereby a circuit is completed from the connection on the potentiometer 15) working contact of spring (51), and said relay (68) to the mid-point of the potentiometer. The relay (68) is energized over this circuit to energize the radio receiving set, and to complete a circuit for the relay 7 O) at armature- (83) over a path that exten s from the connection on the potentiometer (15), armature (83) in its front contacts, contacts (94) relay (70) tothe mid-point of the potentiometer. The relay (70) is energized to open apoint in the circuit of the release magnet (29). The operation of the springs (50) of the key (48) serves to prepare a point on the circuit of the release magnet (29). When the tone arm (5) .7 is moved to its original position, re-set mag net (34) functions as before. So long as the broadcasting station does not again start to broadcast, the record will continue to play. When the record is;

'(9 i). The relay is t ereupon de-en- 'ergized-to complete a circuit for the release In order to relieve the through playing, the rotation of the turn-table will be stopped by the operation of the relay (23) in the same manner as before de-' scribed. Another record may be played in the same manner. It will be assumed that 70 while one of'these records is being played,

the broadcasting is resumed. Under these conditions the voice current relay (65) is operative.tb cause the openin of the springs magnet (29). The release magnet- (29) functions to bring the turn-table to rest, and to disconnect the motor (7). Inasmuch as the radio receiving setis connected with the loud speaker, the broadcast reception is continued as before.

'It will be noted that the magnetic ihk-u is connected to the grid of the ampli er (16) as well as to the secondary of the transformer (58). The current in this circuit is relatively small, andwill not afi'ect the operation of the relay (65) to prevent it from functioning in the manner described. This is true because the current is not amplified at all, before being impressed on the armature of the relay (65).

With the key (48) in the N A position, stations will continue to be tuned in as they sign ofi until the relay (67) is finally-operated to disconnect the energy from the set.

If it is desired to operate the radio alone, the key (48) is thrown into the N A position. The push button (28) is then operated to connect electrical energy to the set. The relay (68) is energized to connect the energy to the radio receivin set. Inasmuch as the relay (22) is energized immediately upon the operation of the rectifiers. 13 and 14), the circuit is complete for the s ow to operate relay (69), and this relay is energized to initiate the automatic tuning. Subsequent operations occur substantially as before described.

It may be that the operator desires to tune in a predetermined station. Inorder that he may do this a calling device (73) is provided, together with a key (93'); This calling device maybe of a type somewhat similar to that employed in the telephone art, though preferably it is modified so that one revolution of the calling device will cause it to close its springs a large number of times. That is, it may be designed to send one hundred impulses. These impulses are adapted to actuate a steppingmagnet (62)'that is arranged to advance the rotor of a condenser (61) through 180 de rees by means of the pawl and ratchet (60 e The call letters of the various broadcast- 1. ing stations may be noted on the dial so that the required number of-impulses may Ill onant, or approximately so, to the broadcasting carrier frequency of the station. The calling device (73) and the key (93') may be located with the phonograph, or at any desired point at a distance therefrom.

In order to properly operate the calling device (73) the operator throws the key (93). As a result of the operation of this key, a circuit is completed after the stepping magnet (62) through the off normal springs (91) and armature (90'). The stepping magnet was intermittently operated by a buzzer action until the rotor of the condenser is placed in its predetermined normal position. At this point the circuit of the stepping magnet is opened at the oil' normal springs (91'). The calling device is then operated so that the desired number of impulses are sent to advance the rotor of the condenser, to the predetermined position. The relay (69) is operated after an interval oftime to complete a circuit for the motor (59) providing the voice current relay (20) has not been operated. The operation of the motor (59) serves to tune in the desired station, inasmuch as the rotor of the condenser has been placed in approximately the desired position, and the subsequent motion of the rotor is merely to tune this station in properly. This result will be brought about if the station is broadcasting, inasmuch as it is the closest station to the setting of the rotor of the condenser. If a station does not happen to be broadcasting at this time, another station will automatically be tuned in, although the operator may press the release key (93) and select another desired station.

It is desirable in some communities where both direct and alternating current is supplied to the various districts, that the machine be adapted to operate equally well with direct current, as well as alternating current. Means provided for accomplishing this result will now bedescribed.

t will be assumed that the source (74) is supplied with direct current. When the button (28) is pressed as before, the relay (66) is energized to connectenergy through the high impedance relay (71). This relay responds to direct current to attract its arma-.

ture (85), thereby completing a circuit for the harmonic relay (72) by way of armature (86), and its back contact. (86) of this relay is tuned as mentioned before to respond to 60 cycles. This armature is also polarized. The armature (86) is now operated so as to break the contact which includes its own circuit. The armature then swings back to again close the circuit. This operation continues at the rate of 60 times a second. The current through the primary of the transformer (12) is thus interrupted 60 times a second. By the action of the transformer, 60 cycle alternating current is The armature induced in the secondary windings; the voltage of this current being proportionatel of the proportion of the turns in the secon ar windings, to the turns in the primary win The relay (72) thus operates essentially in the same manner as the relays employed in the harmonic converters used in the telephone art to create alternating currents. The contacts may be somewhat larger, so that the required amount of current will be supplied to the device. The current impressed upon the rectifiers and the other portions of the circuit is thus substantially the 60 cycle alternatin current of the same character as is obtaine from the usual commercial sources, so that the apparatus will function in the same manner as before. Thus, by the provision of the relay (71) and the harmonic converter (72) whenever the device is connected to a direct current source, the relay (71) is automatically operated to initiate the operation of the harmonic converter (72), to supply alternating current to the device.

It will be seen that I have provided simple and efiicient means for automatically preselecting any one of a. plurality of broadcasting stations, one after the other, for automatically selecting a predetermined broadcasting station, for automatic stoppin of the playing of the record, and the switching in of the radio receiving set at desired times, as well as a number of other desirable features that have been described in the foregorendering said apparatus responsive to different frequencies, means for automatically actuating said element until a station is tuned in, means for automatically tuning in another station when reception from said first station is interrupted, and voice current responsive means for automatically disconnecting said operating current when no waves are received for a predetermined period.

2. In a radio receiving system, a radio apparatus, a tuning element for rendering said apparatus responsive to waves of different frequencies, means for supplying operating current tosaid apparatus, and voice current responsive means for automatically disconnecting said operating current when receptiori is interrupted for a predetermined pe I10( magnet to operate the switch.

JOHN E. GARDNER. 

